Saturday, March 12, 2011

Danger at Fukushima nuclear power plant

"Japan nuclear plant in state of emergency, as cooling power runs low"

A nuclear plant in Japan is said to declare a state of emergency, as backup power used to cool three reactors runs low. Help is on the way. 'It's a dicey situation,' says nuclear specialist in US.


Mark Clayton

March 11th, 2011

The Christian Science Monitor

At least 11 of Japan's 52 nuclear power reactors are shut down and three of those may pose a danger to the public after a massive magnitude 8.9 earthquake hit the island nation Friday. One plant, 150 miles north of Tokyo, is reported to be in a state of emergency. It is relying on limited battery power to cool the three problematic reactors, and officials say they plan to release some radioactive gases to the atmosphere to cope with the problem.

The Japanese government issued an evacuation advisory to people living within a 3-kilometer (1.8-mile) radius of the Fukushima 1 nuclear power plant, according to Japan Broadcasting Corp.'s NHK World website.

Tokyo Electric Power Co. says an equipment failure had made it "impossible to cool two reactors" at the Fukushima 1 plant. Air that may contain radioactive materials will be vented from the plant, the company told NHK World late Friday. The decision to release the gases was to avoid the breakdown of the reactors, the news agency reported. Tokyo Electric told NHK World that the release would be small and that the company will notify residents near the plant before it starts the release and will monitor the amount of radioactivity in the gas.

The company reported that its power plant lacked sufficient electricity to cool the reactors, which automatically stopped operating when the quake struck, NHK World reported. Six reactors are inside Fukushima 1, and three were already offline prior to the quake.

But the quake knocked reactors 1, 2, and 3 offline. Then, about an hour after the quake, the diesel generators that provide emergency power for the cooling system on the reactors failed – putting the system on a battery backup system. Uncooled, a reactor's uranium core can overheat to the point of meltdown, and in a worst case become an event like the 1986 Chernobyl disaster in the Ukraine region of the former Soviet Union, which spread radiation across much of Europe.

Apparently in "a blackout condition," the plant is relying on a Reactor Core Isolation Cooling System backup, which needs batteries for valves, gauges, and instruments – and is reported to have about an eight-hour capacity, says Edwin Lyman, a nuclear specialist with the Union of Concerned Scientists in Washington.

At the time of writing, reactor pressure was said to be rising to dangerous levels inside the Fukushima plant's No. 1 reactor and might require venting [which would that release radiation], and water levels in reactor No. 2 were reported to be dropping [which causes the reactor to overheat], says Dr. Lyman. Failure of the cooling system can lead to a meltdown [of the reactor core], in which fire could release harmful levels of radioactivity into the environment.

"They're operating on battery power now, and if they lose the batteries, they lose core cooling," Lyman says. "The [Japanese] military is supposed to be ferrying in batteries now, but it's a dicey situation."

The military and other authorities are sending power generators to the site, NHK reported. The government characterized the evacuation of residents near the plant as a precaution, and it also asked people living within 10 kilometers (6.2 miles) of the plant to stay indoors, NHK said.

"The government's Nuclear and Industrial Safety Agency says cooling system failure has made it impossible to cool the second reactor after it automatically stopped operating after the earthquake," NHK reported Friday. "The plant has been declared to be in a state of emergency after the quake caused the technical failure."

As is the case in the United States, Japan has requirements that call for nuclear power plants to be able to withstand a serious earthquake. Seismic rules for nuclear plant construction are slightly different from those in the US, but, like the US, fall into two major categories, says Charles Becht V, a senior engineer at Becht Engineering Co. in Liberty Corner, N.J., which has done consulting work in Japan.

First, there is the "operating basis earthquake ground motion," or OBE – quakes that can be expected to occur multiple times in the life of a plant. When such an earthquake occurs, plants are shut down and inspected.

A "design basis earthquake," or DBE, is one so big that it would be expected to occur only once in the life of a plant, Becht explains in an e-mail. The DBE design requirement for a plant simply "requires that a plant can shut down without release of radioactive material.

"Extensive damage is still expected with significant inspection being required for any restart," he writes. "In general, a significant number of systems can become faulted in a nuclear power plant without containment [of radiation] being compromised."

Constructing a nuclear power plant so that it can ride out a major earthquake without damage is possible, but such practice is not widespread, says Michael Constantinou, a civil engineering expert at University of Buffalo, State University of New York, who has studied the issue. Just three plants in the world – two in France and one in South America – use shock absorbers to physically isolate the reactors from surrounding ground movement.

The Nuclear Energy Institute in Washington, a trade group, has been monitoring Japan's nuclear industry website and gathering other information. "From what I understand, they have been able to cool the Fukushima No. 2 reactor with no danger of fuel being exposed [to the air]," says spokesman Mitch Singer. The group characterizes the situation in Japan as safe and stabilizing.

"The most important thing is that the Japanese have it under control," says Mr. Singer. "The emergency shut-down procedures worked as planned. The coolant level may be down, but it's still within the safety margin." He acknowledged that pressure is reported to be rising in the No. 1 reactor but had no further information.

Earlier, a fire was reported in a turbine building of Tohoku Electric Power's Onagawa nuclear plant, which was contained, the Kyodo news agency reported and Mr. Singer confirmed.

President Obama told reporters at a press conference that the US would help Japan if asked and said he was certain that "if in fact there have been breaches in the safety systems of these plants, that they will be dealt with right away."

The Japanese experience highlighted concerns Union of Concerned Scientists has about the adequacy of backup power and other safety systems at the 104 nuclear power reactors across the US, Lyman says. The group backs nuclear power as one option to help combat climate change, but has concerns about plants' safety.

"We do not think safety standards for US nuclear reactors are enough to protect the public today," he says in an interview.

The US Nuclear Regulatory Commission said its standards are sufficient.

"Nuclear power plants are built to withstand environmental hazards, including earthquakes and tsunamis," the NRC said in a press release. "Even those plants that are located outside of areas with extensive seismic activity are designed for safety in the event of such a natural disaster."

After the quake in Japan, the NRC said it is monitoring the two nuclear reactors at the Diablo Canyon Power Plant, located on the coast near San Luis Obispo, Calif., because of the West Coast tsunami warning Friday morning.

“The NRC is closely monitoring this situation as it unfolds with respect to nuclear facilities within the United States. NRC staff is working closely with its resident inspectors who are on site to ensure safe operations,” said NRC Chairman Gregory Jaczko, in a statement.

Both Diablo Canyon reactors are stable and both units remain on-line. The plant is "well protected against tsunami conditions as required by NRC regulations" and has NRC staff on site to track its response.

Events in Japan could have a negative impact on American attitudes as the nuclear power industry in the US pushes for a "nuclear renaissance" and more non-greenhouse-gas-emitting power sources, some energy analysts said.

"Nuclear power’s status as a 'clean fuel' could be compromised," writes Kevin Book, senior analyst for CleanView Energy Partners, a Washington energy markets research firm. "Although events in Japan may actually validate the safety of nuclear power despite a severe earthquake, energy accidents that can reach well outside the immediate sites of production carry a significant political 'fear factor.' ”

"Japan's fears mount with nuclear plant blast"

Officials try to calm residents wary of a possible radiation leak -- or worse -- at the Fukushima power plant, which lost its cooling system in Friday's massive earthquake. Nationwide, the death toll from the quake and tsunami could top 1,700.


Mark Magnier, Barbara Demick and Carol J. Williams

March 12th, 2011

Los Angeles Times

A day after responding to one of the worst earthquakes on record and a massive tsunami, the Japanese government sought to allay fears of a radioactive disaster at a nuclear power plant on the country's battered northeastern coast.

The outer walls of the Fukushima power plant's No. 1 reactor were blown off by a hydrogen explosion Saturday, leaving only a skeletal frame. Officials said four workers at the site received non-life-threatening injuries.

The inner container holding the reactor's fuel rods is not believed to be damaged, said Japan's Chief Cabinet Secretary Yukio Edano, and workers were cooling the facilities with seawater.

In a press conference shortly after the explosion, which left the facility shrouded in plumes of gray smoke, Edano explained that the reactor is contained within a steel chamber, which in turn is surrounded by a concrete and steel building. Although the explosion destroyed the building, it did not occur in the chamber.

"The escape of hydrogen mixed with the air between the chamber and the concrete-and-steel building and led to the explosion," Edano said.

"Tokyo Electric Power Co. has confirmed that the inner reactor is undamaged," he added. "There was no massive release of radiation."

Still, the reactor was already showing signs of a partial meltdown after Friday's magnitude 8.9 earthquake had prevented the plant 150 miles north of Tokyo from fully powering its water cooling system. Without it, the facility could overheat and explode, spewing radioactive into the air.

Edano said experts were still determining what caused the blast.

"We are doing everything to ensure the safety of residents living nearby," said Edano, the government's chief spokesman. "I'm sure residents [living nearby] are feeling unease."

People were reportedly fleeing the surrounding area and Japanese television was urging people to cover their faces with wet towels and not to expose any skin to the potentially contaminated air. An evacuation zone was doubled to a 12-mile radius around the plant by Saturday evening.

"By taking all these appropriate measures, we would like to avoid any situation where any people's health is damaged," said Japanese Prime Minister Naoto Kan at a press conference. "This is an unprecedented disaster we're suffering."

Earlier in the day, workers had been racing to prevent the No. 1 reactor from over-heating by releasing accumulated vapor.

Officials of Japan's Nuclear and Industrial Safety Agency had insisted that the "slightly radioactive" emissions release posed no risk to people or the environment. Radiation levels inside the overheated reactor housing were 1,000 times normal, the agency said, but only eight times normal background at the plant's main gate. Experts explained that the steam carries low-level radiation that rapidly dissipates.

Japan relies on nuclear power for a third of its electricity and is said to require exacting safety standards for its plants.

The radiation scare comes on a day most of Japan was still trying to dig-out from an earthquake that's believed to have killed 1,700 people so far with countless still missing under rubble and muddy debris.

Japanese self-defense forces reportedly found 400 bodies in the seaside town of Rikuzentakata in Iwate prefecture. Television showed a rising tide rolling into the community, first filling the gaps between buildings before finally swallowing the city past its rooftops.

The force of the magnitude of Frida's quake, which seismologists said released 1,000 times the energy of the January 2010 earthquake in Haiti, broke the foundations under homes and buildings and opened chasms in fields and pavement, swallowing cars and shearing off sidewalks and driveways.

More than 100 aftershocks have jolted Japan since Friday's 2:46 p.m. temblor, including at least a dozen of magnitude 6 or higher, said Dave Applegate, a senior advisor at the U.S. Geological Survey.

The earthquake, centered just off the northeastern coastal city of Sendai, was the most powerful since a December 2004 quake and ensuing tsunami killed 230,000 people in Indian Ocean nations.

The havoc unleashed on Japan just ahead of Friday rush hour has left the nation mired in fear, suffering and hardship. Millions of people are without power, utility officials said, and they warned that outages would continue through the weekend, with rolling blackouts persisting for weeks.

Four trains carrying passengers along the coast at the time of the quake remain unaccounted for, East Japan Railway Co. reported. Television footage showed two passenger train carriages half submerged under water by the coast.

Only half of the hundreds of people reported trapped in elevators were rescued overnight, according to the Ministry of Land, Infrastructure, Transport and Tourism.

Key rail lines remained idle for a second day because of damaged track, tunnels and bridges. Service on Tokyo's vaunted subway system, the world's busiest with 8 million passengers per day, was sharply reduced pending safety inspections.

Limited air traffic resumed at major airports, including Tokyo's Narita International, but most were thronged by travelers marooned after major airlines suspended flights.

Steven Nia, a Los Angeles businessman heading for a flight home at the airport, said he slept the night in the terminal.

"I'm from California, so I recognize what an earthquake is, but I've never seen anything like this," Nia said.

Tokyo Bay, one of the busiest harbors in the world, was eerily quiet Saturday afternoon. Ships, barges and fishing boats sat idle in the still waters. The freeway across the bay was empty.

At Tokyo's railway station, hordes of people were making their way home after spending the night stranded in the capital.

Kenji Higuchi, 43, manager at the radio communications provider Japan Enix Co., said he spent the night monitoring and inspecting wireless base stations across Tokyo and slept in his office. He had to jostle for 10 minutes with throngs trying to board suburban trains just to get on the platform, he said.

"The images of destruction and flooding coming out of Japan are simply heartbreaking," President Obama told a news conference at the White House. He said the U.S. aircraft carrier Ronald Reagan was heading toward Japan to join the U.S. 7th Fleet's command ship, Blue Ridge, in the massive global relief effort.

Obama said he had spoken with the Japanese prime minister to extend condolences and "offered our Japanese friends whatever assistance is needed."

At least 45 countries scrambled disaster-relief teams, including 68 search-and-rescue units that were awaiting the Japanese government's direction on where to deploy, said Elisabeth Byrs of the U.N. Office for the Coordination of Humanitarian Affairs. A team of disaster responders sent to New Zealand by Tokyo after the Christchurch earthquake last month rushed back to help their devastated homeland.

The Defense Ministry said about 20,000 Self-Defense Forces troops, 190 aircraft and 25 vessels had been dispatched Saturday to the area around Sendai, where tsunami waves a day earlier churned whole neighborhoods into debris, crashing through homes and businesses and sweeping trains, trucks and cars into the moving mass of destruction.

Ministry officials were working with the Pentagon on plans to use U.S. naval forces to move 250 rescue vehicles into areas rendered unapproachable by waves that washed away roads and rail lines.

About 69,000 people were stranded at Tokyo Disneyland and Tokyo DisneySea because of road damage and idled mass transit. Theme park workers gave out blankets, heaters and coats to visitors forced to camp outside in 30-degree temperatures.

"Rations and supplies are just starting to reach emergency shelters," said Cabinet Secretary Yukio Edano, dressed in the light-blue jacket that identifies disaster-relief workers.

Images from the coastal city of Soma taken from a TV network helicopter showed trees that had been uprooted by the tsunami and then dragged back to shore when the waters receded.

Video taken over Kesennuma, in Miyagi prefecture, where the quake was most destructive, captured a Self-Defense Forces helicopter swooping low over a neighborhood to pluck a survivor from one of the few rooftops still above water.

In Iwanuma, survivors taking refuge on top of Minamihama Chuo Hospital waved flags and umbrellas to signal for help. All around them were water and the debris of buildings.

At Sendai airport, a small private jet appeared to have been carried by the rushing waters and left partly buried in waterlogged rubble. Most of the runway was under water.

Crews labored through the night to dig out trucks and cars that had fallen into chasms in roads and highways. At a Machida district shopping center in Tokyo, the ramp of a parking lot had collapsed, and workers with cranes were searching for people in the wreckage. One person pried from the rubble was unconscious and in critical condition.

"More than 90% of the houses in three coastal communities have been washed away by tsunami," a municipal official in the town of Futaba told the Kyodo News Agency. He said from his vantage point on the fourth floor of the town hall, "I see no houses standing."

Prime Minister Kan visited the stricken nuclear facility in a tour of the disaster areas. He vowed to "make whatever decisions need to be made" as he boarded a helicopter for the aerial tour.

Japan's nuclear facilities have survived many earthquakes. But the Kashiwazaki-Kariwa facility, the world's largest, was forced to close for two years in 2007 after being hit by an earthquake of greater force than the plant was designed to withstand. And Japan has a record of cover-ups when it comes to nuclear accidents. In 2007, the operators of the Shika plant acknowledged they had failed to report a 15-minute uncontrollable nuclear chain reaction eight years earlier. Another operator was forced to close 17 plants temporarily in 2003 after admitting it falsified safety inspection reports.

Japanese Finance Minister Yoshihiko Noda said the government would tap a contingency fund to cope with the massive damage, according to Kyodo New Agency.

Japan is already facing some of the highest public debt of any industrialized nation, running at about 200% of its annual economic output.

"To be honest I'm worried about the economy in the short term," said Kazu Hoshiai, 43, a Japan Airlines worker. "We are accustomed to earthquakes but not like this one."

"Explosion Rocks Japan Nuclear Plant After Quake"


Matthew L. Wald

March 12th, 2011

The New York Times

An explosion at a nuclear power plant in northern Japan on Saturday blew the roof off one building, brought down walls and caused a radiation leak of unspecified proportions, Japanese officials said, after Friday’s huge earthquake caused critical failures in the plant’s cooling system.

Television images showed a huge cloud of white-gray smoke from the explosion. Soon afterward, government officials said an evacuation zone around the plant had been doubled, to 12 miles. The chief cabinet secretary, Yukio Edano, confirmed earlier news reports of an explosion at the Fukushima Daiichi nuclear plant, 15o miles north of Tokyo, saying: “We are looking into the cause and the situation and we’ll make that public when we have further information.” He was speaking amid fears that a disastrous meltdown could be imminent because of critical cooling failures at that plant and another nearby, Daini, after both were shut down.

Images on Japanese television showed that the walls of one building had crumbled, leaving only a skeletal metal frame standing with smoke billowing from the plant. The Associated Press reported that the damaged building housed a nuclear reactor, though that report was not immediately verified by nuclear officials. The cause of the explosion was unclear, with some experts speculating that it may have resulted from a hydrogen build-up.

There was no immediate confirmation of news reports that the container of the nuclear reactor itself had escaped damage.

Bloomberg News quoted Tokyo Electric Power Co., the plant’s operator, as saying the explosion happened “near” the No. 1 reactor at around 3:40 p.m. Japan time on Saturday. Four people were reported injured. The explosion came roughly 26 and a half hours after an 8.9-magnitude earthquake caused a deadly tsunami that killed hundreds and caused both plants to be shut down. Authorities issued broad evacuation orders on Saturday for people living near the plants and warned that small amounts of radioactive material were likely to leak out.

Officials said even before the explosion that they had detected cesium, an indication that some of the fuel was already damaged.

In the form found in reactors, radioactive cesium is a fragment of a uranium atom that has been split. In normal operations, some radioactivity in the cooling water is inevitable, because neutrons, the sub-atomic particles that carry on the chain reaction, hit hydrogen and oxygen atoms in the water and make those radioactive. But cesium, which persists far longer in the environment, comes from the fuel itself.

Naoto Sekimura, a professor at Tokyo University, told NHK, Japan’s public broadcaster, that “only a small portion of the fuel has been melted. But the plant is shut down already, and being cooled down. Most of the fuel is contained in the plant case, so I would like to ask people to be calm.”

Failure of the cooling systems allowed pressure to build up beyond the design capacity of the reactors. Small amounts of radioactive vapor were expected to be released into the atmosphere to prevent damage to the containment systems, safety officials said. They said that the levels of radiation were not large enough to threaten the health of people outside the plants, and that the evacuations had been ordered as a precaution.

Nuclear safety officials focused initially on the Daiichi plant. But by Saturday morning Japan had declared states of emergency for five reactors at the two plants, an escalation that added to worries about the safety of nuclear facilities in the quake-prone Japanese islands.

The Daiichi and Daini plants are 10 miles apart in Fukushima Prefecture, close to the quake’s epicenter off the coast.

The plants’ problems were described as serious but were far short of a catastrophic emergency like the partial core meltdown that occurred at the Three Mile Island plant near Harrisburg, Pa., in 1979.

A Japanese nuclear safety panel said the radiation levels were 1,000 times above normal in a reactor control room at the Daiichi plant. Some radioactive material had also seeped outside, with radiation levels near the main gate measured at eight times normal, NHK quoted nuclear safety officials as saying.

The safety officials said there was “no immediate health hazard” to residents from the leaks, which they described as “minute,” and people were urged to stay calm.

The emergency at the Daiichi plant began shortly after the earthquake struck on Friday afternoon. Emergency diesel generators, which had kicked in to run the reactor’s cooling system after the electrical power grid failed, shut down about an hour after the earthquake. There was speculation that the tsunami had knocked the generators out of service.

Twenty hours later, the plant was operating in a battery-controlled cooling mode. Tokyo Electric said that by Saturday morning it had installed a mobile generator at Daiichi to ensure that the cooling system would continue operating even after reserve battery power was depleted. Even so, the company said it was considering a “controlled containment venting” in order to avoid an “uncontrolled rupture and damage” to the containment unit.

“With evacuation in place and the oceanbound wind, we can ensure the safety,” a nuclear safety official, Yukio Edano, said at a news conference early Saturday.

It was not clear, however, how long the cooling systems could continue to function in emergency mode or when normal power supplies could be restored.

Two workers were reported missing at the Daiichi plant, but the company did not explain what might have happened to them.

A pump run by steam, designed to function in the absence of electricity, was adding water to the reactor vessel, and as that water boiled off, it was being released. Such water is usually only slightly radioactive, according to nuclear experts. As long as the fuel stays covered by water, it will remain intact, and the bulk of the radioactive material will stay inside. If the fuel is exposed, it can result in a meltdown.

The reactors at the two plants initially shut down when the earthquake began at 2:46 p.m. Friday. But emergency diesel generators at the Daiichi plant went down a little less than an hour later, and pressure began to rise in the reactor, leading operators to vent it.

During much of the early morning on Saturday, safety officials focused on getting emergency power supplies to the Daiichi plant to restore the normal cooling function.

Secretary of State Hillary Rodham Clinton, speaking in Washington, said that American military planes had already delivered “coolant.” But American military officials indicated that while they were prepared to help Japan grapple with any problems related to its nuclear facilities, they had not been asked to do so.

Japan relies heavily on nuclear power, which generates just over one-third of the country’s electricity. Its plants are designed to withstand earthquakes, which are common, but experts have long expressed concerns about safety standards, particularly if major quake hit close to a reactor.

One major concern is that while plant operators can quickly shut down a nuclear reactor, they cannot allow the cooling systems to stop working. Even after the plant’s chain reaction is stopped, its fuel rods produce about six percent as much heat as they do when the plant is running. The production of heat drops off sharply in the following hours, but continued cooling is needed or the water will boil away and the fuel will melt, releasing the uranium fragments inside.

Heat from the nuclear fuel rods must be removed by water in a cooling system, but that requires power to run the pumps, align the valves in the pipes and run the instruments. The plant requires a continuous supply of electricity even after the reactor stops generating power.

With the steam-driven pump in operation, pressure valves on the reactor vessel would open automatically as pressure rose too high, or could be opened by operators. “It’s not like they have a breach; there’s no broken pipe venting steam,” said Margaret E. Harding, a nuclear safety consultant who managed a team at General Electric, the reactors’ designer, that analyzed pressure buildup in reactor containments. “You’re getting pops of release valves for minutes, not hours, that take pressure back down.”

Civilian power reactors are designed with emergency diesel generators to assure the ability to continue cooling even during a blackout. Many reactors have two, assuring redundancy; some have three, so that if one must be taken out of service for maintenance, the plant can still keep running.

It was not immediately clear how many diesel generators there are at Daiichi, but the operators reported earlier in the day that they were not working, prompting the evacuation.

Daiichi, which is formally known as Fukushima Daiichi Nuclear Power Station, was designed by General Electric and entered commercial service in 1971. It was probably equipped to function for some hours without emergency diesel generators, said David Lochbaum, who worked at three American reactor complexes that use G.E. technology.

Mr. Lochbaum, who also worked as an instructor for the Nuclear Regulatory Commission on G.E. reactors, said that such reactors were equipped to ride out interruptions in electrical power by using pumps that could be powered by steam, which would still be available in case of electric power failure. Valves can be opened by motors that run off batteries, he said. Plants as old as Fukushima Daiichi 1 generally have batteries that are large enough to operate for four hours, he said.

After that, he said, the heat production in the core is still substantial but has been reduced. The heat would boil away the cooling water, raising pressure in the reactor vessel, until automatic relief valves opened to let out some of the steam. Then the valves would close and the pressure would start building again.

If the cooling system remains inoperative for many hours, the water will eventually boil away, he said, and the fuel will begin to melt. That is what happened at Three Mile Island. In that case, the causes were mechanical failure, operator error and poor design, according to government investigators.

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